Illuminating- apparatus



E. A. HAWTHORNE.

ILLUMINATING APPARATUS.- APPLICATION man DEC-6, 1911.

Patented Apr 13, 1920.

3 SHEETS-SHEET 2.

' Inventor: Eaaworikflflawihom,

E. A. HAWTHORNE.

ILLUMIINATING APPARATUS.

APPLICATION FILED DEC-6, 1917.

. 1 33 37; Patented Apr. 13, 1920.

3 SHEETS-"SHEET 3.

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ELLSWORTH A. HAWTHORNE, OF BRIDG-EPORT, CONNECTICUT.

ILLUMINATING APPARATUS.

Specification of Letters Patent.

Patented Apr. 13, 1920.

Application filed December 6, 1917. Serial No. 205,715.

To all whom it may concern Be it known that I, ELLswoRTH A. HAW- rr-ronnn, a citizen of the United States, and a resident of Bridgeport, in the county of Fairfield and State of Connecticut, have invented an Improvement in Illuminating Apparatus, of which the following description, in connection with the accompanying drawings, is a specification, like characters on the drawings representing like parts.

This invention relates to illuminating apparatus, and is more especially though not exclusively concerned with a head lamp for vehicles, the same being more especially concerned with a vehicle head lamp having means for furnishing a far-reaching beam of light to illuminate a distant roadway, as well as a widely spread light for illuminating the foreground and objects at the sides of the roadway, while still preventing glaring or blinding rays above a certain height from the roadway.

My invention will be best understood by reference to the following description, when taken in connection with the accompanying drawings of one illustrative embodiment thereof, while its scope will be more particularly pointed out in the appended claims.

In the drawings:

Figure 1 is a front element of an illuminating apparatus embodying my invention;

Fig. 2 is a sectional view on line 2-2 of Fig. 1, illustrating in a diagrammatic way the action of the light rays;

Fig. 3 is a sectional View on line 33 of Fig. 1, also illustrating in a diagrammatic way the action of the light rays;

Fig. i is a sectional view on the are H in Fig. 1, showing the prismoids incrosssection;

Fig. 5 is an enlarged sectional view on line 55 of Fig. 1, illustrating the action of the light rays;

Fig. 6 is a sectional View on line 66 of Fig, 1, illustrating the action of the light rays; and v Fig. 7 is a front elevation of a portion of the illuminating apparatus illustrating the action of some of the, light rays and showing how those of one set cross those of another.

Referring to the drawings, and to the embodiment of my invention which is illustrated therein, I have shown a vehicle head lamp comprising a suitable light source 8, which may be and herein is in the form of an incandescent electric bulb. Associated with the light source is a suitable light-cons centrating and projecting means which may be and herein is in the form of a parabolic reflecting surface 9, which may be of any suitable depth and focal length to suit the particular circumstances. Associated with the light source and reflector are suitable means to intercept upwardly directed rays, means to deflect other rays, and means to transmit still other rays without substantial deflection.

In the present example, I have shown a lens designated generally by the numeral 10, preferably having a substantially flat smooth front face, and having a suitable light-transmitting portion 11, whose rear face is also substantially flat and parallel with the front face, whereby some light rays are transmitted without substantial deflection as a focalized, substantially parallel beam, to illuminate the distant roadway. Preferably this portion is located largely below the axis AA of the reflector, light source and lens. Preferably, also, this portion is generally circular, or rather in the form of a large sector, although this is not at all essential.

In the accompanying drawings, the direct un-reflected rays are shown in light lines, while the reflected rays, which in the present example are emitted as a substantially parallel focalized beam, are shown by way of contrast by relatively heavy lines.

Referring now to Figs. 2 and 3, and hav ing reference to the plain light-transmitting portion 11, I have shown a plurality of focalized reflected rays a, which emerge without substantial deflection. This provides from the lower portion of the reflector a powerful and far-reaching parallel beam for theillumination of the distant roadway. I have also shown in Figs. 2 and 3, a plurality of direct, unreflected rays Z), emerging through the plain portion 11 and adapted to illuminate the less distant roadway and a considerable part of the foreground.

As a means for deflecting some of the light rays laterally and in a downward direction, I may employ a plurality of suitable prismoids arranged in any appropriate manner, but in the present example. I have shown a plurality of sets of generally radial prismoids radiatin from the plain portion 11 of the lens. Referring to Figs. 1 and 1, l have shown two similar sets or groups of prismoids 12 on opposite sides of a vertical plane containing the axis A---A of the lamp, and two other sets or groups 13--l3, also on opposite sides of said plane. fly reference to Figs. 1 and 4:, it will be observed that the prismoids of the group 12 face in one direction, while those of the group 1 face in the opposite direction. It should also be observed that the prismoids of one group 13 face in the opposite direction from the prismoids of the other group 13, and that similarly the prismoids of one of the groups 12 face oppositely with reference to the other group 12. In any given group of prisnioids the angle of refraction of each prismoid differs from that of all the others of such group, as will be evident from an inspection of Figs. 4, 5 and 6, which show the prismoids in cross-section. To particularize, referring to the group 12, the same comprises a series of prismoids let to 22, inclusive, which as viewed in Fig. -'lare of progressively increasing thickness. To put it another way, the section of each prismoid may be likened to a. right-angled triangle BUD (see Fig. 5), of which the hypothenuse BC lies in the plane EE of the outer flat face of the lens. The length of the hypothenuse is the same in each prismoid, but the length of the short est side B1) of the triangle varies with each prismoid, the result being that the third side CD which lies in the inner refracting surface of the prismoid differs from each of the others in its angular relation with the axis A-A of the lens. Similarly, the group 13 comprises a plurality of series of prismoids 23 to 29, inclusive, having like characteristics.

Considering now the effect of the crosssectional shape of the prismoids, and referring to Fig. 5, 1 have shown therein a plurality of reflected rays 0 and a plurality of direct, unreflected rays (Z. I shall explain the action of one ray of each kind with reference to the prismoi d 21. Referring to Fig. 5, the reflected ray 0 strikes the inner face of the prismoid obliquely at the point F. On entering the glass, it is reflected toward the normal, and. on emerging from the glass into the air at the point G, it is refracted away from the normal. The total change of direction is the sum of the two partial changes, and is equal to the angle GHF, which is the angle of deflection of the ray. This angle changes with every prismoid, because the angle of the inner face of each prismoid differs from all the others. as previously explained. As the index of refraction from air to crown glass is about 3 :2, and as the angle of refraction is smaller or larger than the angle of incidence, according as the light passes from a rarer to av denser medium, or the reverse, with this set of prismoids the diffusion of the rays is considerable. The action of the ray (Z is similar to that of the ray 0, and need not be explained in detail. It should now be apparent that each prismoid of each group 12 bends or deflects in a downward direction every ray which strikes the same, and by reference to Fig. 3, it will be observed that each of these rays thus deflected is inclined in a downward direction with reference to a horizontal plane 1l, containing the axis A-A of the lens.

Referring now to Fig. 6, I have shown a plurality of reflected rays 6, and a plurality of unreflected rays Considering the action of two of these rays on one of the prismoids 28, for example, it should be noted that each ray is bent or deflected in a manner similar to that hereinbefore explained in connection with the prismoid 21, but in the case of the prismoid 28, since the latter is in a generally upright position, the rays will be bent or deflected in an outward direction with relation to a vertical plane J-J containing the axis ll. A of the lens.

Preferably the inner faces of all ofthe prisms are inclined not only transversely as already explained, but longitudinally as well, as best shown in Fig. 3. In this view, which shows two opposite prismoids 21 in longitudinal section, it is apparent that the face of each prisinoid is inclined not only with reference to a horizontal plane l-l (see Fig. 1) containing the axis of the lens, but also with reference to a vertical plane J J (Fig. 1) containing said axis. The second angle of inclination is well illustrated in Fig. 3. In this view, I have shown a plurality of reflected rays g, and a plurality of direct rays 71 all of which are bent or deflected laterally by the prisms 21, the rays on each side of the axis being deflected in an outward direction with reference to the axis. This should be readily understood without further explanation, as the action is similar to that explained in connection with Figs. and (3. Now, comparing Figs. 3 and 5, I have, for the sake of convenience, given the rays which pass through the prismoid 21 in Fig. 3 different letters of reference from those which pass through said prismoids in 5, and as a matter of fact, they may be actually different sets of rays. How yer, it must now be evident that when a ray, either direct or reflected, strikes one face of any prismoid, such for example as the prismoid 21 in Figs. 3 and 5, such ray will be bent laterally as well as in a downward direction. This not only prevents glaring rays from reaching an eye above the axis of the lamp, but also serves the better to illuminate the foreground, and the sides of the roadway.

Referring now to Fig. 7, l have illustrated in a diagrammatic way how the bent or deflected rays from the four groups 01": prismoids 12, 12, and 13, 13, cross one another. lay an examination of this figure, it is evident that this crossing of the rays causes a diltusion oi the light, and an even illumination of the foreground through a wide angle, thus illuminating objects at each side oi" the roadway, this being of great advantage when the vehicle is rounding a turn. Under such circumstances, although the headlights are pointed straight ahead and toward the outside of the curve, yet the action or the prismoids is such as to afford a widely spread sector of light to a suflicient width to insure ample illumination of the inside of the curve of the roadway, thus insuring safe driving without the necessity of resorting to auxiliary dirigible lamps.

It should now be observed that above the level of the prismoids, there is a large plain sector of the lens which would emit glaring or dazzling rays, if it were not for the provision of suitable means to intercept such rays. Some of the rays are direct or unreflected, while others are rays which would otherwise be reflected by the parabolic reflector 9. As a means for intercepting all such rays, 1 have herein provided suitable light intercepting means which may be in the form of a shield 30 consisting of a segment of a cylindrical tube, and a segment 31 of a disk (see Figs. 1, 2 and 3). Preferably though not necessarily, the parts 30 and 31 are formed as a single piece, and they are preferably though not necessarily madeof some suitable material which will reflect the rays of light striking the same. I prefer to make these parts of some suitable light metal, such as aluminum, which will take a high polish and yet which is light in weight. The shield is placed preferably coaxially with reference to the axis AA of the lens, light source and reflector, and it is preferably though not necessarily secured to the lens by any suitable means, such for example as a bolt 32 which passes centrally through the lens. The part 30 is preferably extended rearwardly into close proximity to the reflecting surface 9, and hence intercepts all rays coming within its scope which would otherwise reach said sur face and be reflected and projected. Some of these rays, as for example the rays 2' in l 2, are reflected by the internal polished surface of the part 30, and thus add to the volume of light which is shed upon the foreground.

While 1 have herein shown and described one specific embodiment of my invention for illustrative purposes, and have disclosed and discussed in detail the construction and arrangement incidental to one specific application thereof, it is to be understood that the invention is limited neither to the mere details or relative arrangement of parts, nor to its specific embodiment herein shown, but that extensive deviations from the illustrated form or embodiment of the invention may be made, without departing from the principles thereof.

Having thus described my invention, what 1 claim and desire by Letters Patent to secure is:

1. In an illuminating apparatus, the combination of a light-source, a light-concentrating and projecting reflector, a lens having a plain portion located below the axis for transmitting some oi the raysas a beam without substantial deflection, a plurality of generally radial prismoids radiating from said plain portion below said axis, and means above said axis for intercepting upwardly directed rays.

2. In an illuminating apparatus, the combination of a light-source, a light-concentrating and projecting reflector, a lens having a plain portion located below the axis for transmitting some of the rays as a beam without substantial deflection, a plurality of generally radial prismoids radiating from said plain portion below said axis, said prismoids including some which deflect rays across the rays deflected by others, and means above said axis for intercepting upwardly directed rays.

3. 111 an illuminating apparatus the combination of a light source, a light concentrating and projecting reflector, a lens having a plain lower middle portion, a series of radiating prisms bounding the same and means for deflecting downwardly rays from the light source projected above the axis.

a. In an illuminating apparatus the combination of a light source, a light'concentrating and projecting reflector, a lens having a plain lower middle portion, a series of radiating prisms bounding the same and a reflector overlying the light source to intercept rays projected above the axis and reflect them downwardly through said plain portion.

5. A lens for a lamp having an eccentric plain portion surrounded by radial prismoids.

6. in an illuminating apparatus the combination of a light source, a light concentrating and projecting reflector, a lens having a plain lower middle portion, prismoids surrounding said portion and arranged to deflect rays to cross closely adjacent the front of the reflector and means to prevent the projection of divergent rays above the axis.

7. In an illuminating apparatus the combination of a light source, a light concentrating and projecting reflector, a lens having a plain lower middle portion, prismoids surrounding said portion and arranged to deflect rays sharply downwardly and laterally and means to prevent the projection of divergent rays above the axis.

8. 111 an illuminating apparatus the combination of a light source, a light concen- 5 trating and projecting reflector, a lens having a plain lower middle portion, prisznoids surrounding said portion and arranged to deflect rays sharply downwardly and laterally and means to reflect rays divergiiq: upwardly from said light source down- 10 Wardly through said plain portion.

In testimony whereof, I have signed my name to this specification.

ELLSWUETH A. PA VTHORNE. 

